Quantum physics just got less complicated with 'Rosetta Stone' breakthrough

Quantum physics says that particles can behave like waves, and vice versa. Researchers have now shown that this 'wave-particle duality' is simply the quantum uncertainty principle in disguise(Timothy Yeo / CQT, National University of Singapore)

Quantum physics is less mind boggling than once thought, experts have said after discovering two strange features of the quantum world are actually the same thing.

Published in the journal Nature Communications, researchers found that 'wave-particle duality' is just a different manifestation of the quantum 'uncertainty principle'.

Still confused?

Wave-particle duality is the idea that a quantum object could behave like a wave. However, the wave behaviour disappears if you try to locate it.

It can be seen when single particles are fired one by one at a screen containing two narrow slits – the particles pile up behind the slits as a stripy pattern like you would expect from waves, not in two heaps as classical objects would. However, when you look at which slit a particle goes through the interference pattern vanishes.

Quantum uncertainty says that it is impossible to know certain pairs of things about a quantum particle at once ie the more you know the position of an atom, the less able you are to know the speed it is moving. The principle is a limit on the knowability of nature.

Researchers from the Centre for Quantum Technologies at the National University of Singapore note that these two concepts have been part of quantum physics for over 100 years.

Researcher Patrick Coles said: "We were guided by a gut feeling, and only a gut feeling, that there should be a connection."

The scientists are all experts on equations that reveal how much can be learned about pairs of properties affected by the uncertainty principle. These are known as 'entropic uncertainty relations'.

They discovered that all the maths previously used to describe wave-particle duality can be reformulated in terms of these relations.

Stephanie Wehner explained: "The connection between uncertainty and wave-particle duality comes out very naturally when you consider them as questions about what information you can gain about a system. Our result highlights the power of thinking about physics from the perspective of information."

Coles added: "It was like we had discovered the 'Rosetta Stone' that connected two different languages. The literature on wave-particle duality was like hieroglyphics that we could now translate into our native tongue. We had several eureka moments when we finally understood what people had done."

The authors say their discovery gives a greater insight into quantum physics and will allow for new ideas for wave-particle duality applications.